Engineering multiple defect sites on ultrathin graphitic carbon nitride for efficiently photocatalytic conversion of lignin into monomeric aromatics via selective C–C bond scission

• Published in: Applied surface science Vol. 643; p. 158653
• Main Authors: Cao, Mengyu, Shao, Shibo, Wei, Wenjing, Love, Jason B., Yue, Zongyang, Zhang, Yiming, Zhang, Xiaolei, Xue, Yuxiang, Yu, Jialin, Fan, Xianfeng
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.01.2024
• Subjects: C–C bond cleavage; Graphitic carbon nitride; Lignin conversion; Photocatalysis; Lignin conversion; Photocatalysis; C–C bond cleavage; Graphitic carbon nitride
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2023.158653

[Display omitted] •Ultrathin g-C3N4 with multiple defects was prepared by a novel synthesis method.•The created defects are active sites for the essential reactive radicals generation.•The catalytic activity for C–C bonds cleavage was improved 100% by created defects.•Various lignin models can be converted to monomeric aromatics by C–C bonds cleavage.•Lignin biomass can also be decomposed to aromatic monomers by the developed g-C3N4. Lignin depolymerisation via photocatalytic cleavage of the selective interunit linkage in lignin could be a sustainable approach to produce monomeric aromatic chemicals. However, the insufficient investigation of interunit C–C bond fragmentation has obstructed the rational design of efficient photocatalytic system and further limit the yields of aromatic monomers from lignin depolymerisation. Herein, this work developed the ultrathin g-C3N4 with multiple defective sites by simple self-assembly process and in-situ thermal gas-shocking/etching process to catalyse the cleavage of lignin C–C bonds under visible light irradiation. Compared with the pristine g-C3N4, the developed g-C3N4 photocatalyst exhibited a superior catalytic activity (improved 102 %) and selectivity (∼90 %) in the cleavage of C–C bonds in lignin. This study demonstrated that the defects construction and ultrathin structure can optimise the electronic structures of g-C3N4 for better separation and transfer of photoinduced charges. And the control experiments and DFT calculation indicated that the created defect sites can promote the generation of essential reactive radicals (e.g., the activation of O2) and radical intermediates (C–H activation). The present work provides useful insights for the rational use of defect engineering in designing the efficient photocatalytic system for the conversion of lignin into aromatic monomers via the C–C bond cleavage.